Adds browser specific prefixes and returns resulting css.

<div class="definition">
    w2utils.cssPrefix(prop, val, returnString)
</div>

<div class="arguments">
    <table>
    <tr>
        <td>prop</td>
        <td><b>string</b>, css property</td>
    </tr>
    <tr>
        <td>val</td>
        <td><b>string</b>, property value</td>
    </tr>
    <tr>
        <td>returnString</td>
        <td><b>boolean</b>, return as string instead of object</td>
    </tr>
    </table>
</div>

This method is used internally in grid, popup, etc. But you can use it as well. It will add prefixes "-webkit", "-moz", "-ms", "-o" and return resulting object.

<textarea class="javascript">
var style = w2utils.cssPrefix('transition', '1s')
console.log(style); // shows {transition: "1s", -webkit-transition: "1s", -moz-transition: "1s", -ms-transition: "1s", -o-transition: "1s"}
</textarea>
